The invention relates to a braking correction device comprising two correcting valves and intended for a dual hydraulic brake circuit in a motor vehicle.
In a dual circuit of this type, the correcting valves generally have inlets separately connectible to two independent braking pressure sources and outlets to two independent sets of brake actuators, each valve being capable of controlling the pressures at its inlet and outlet in accordance with a predetermined relationship. The valves used are either of the pressure limiting type, in which the pressure at the outlet is limited to a predetermined value, or of the proportional pressure-compensating type, in which the pressure at the outlet increases, beyond a transition pressure, proportionately to but less than the increase in the pressure at the valve inlet. Each valve has a piston subject to resilient return means which may be associated with means for detecting the load applied to at least one axle of the vehicle. It has been customary hitherto, in the case of dual corection devices, to connect the resilient return means to the pistons of the two valves by a mechanical rod and beam system. The mechanical systems used are not always very reliable due to vibrations on the vehicle, and also it is difficult to ensure that the return forces acting on each valve piston are accurately distributed. The operating characteristics of the two independent brake circuits associated with the respective correcting valves have therefore been appreciably different, with a consequent risk of unbalancing the vehicle's braking. This disadvantage is found particularly in dual circuits in which the valves are arranged either "crosswise" or "double-L", with each valve controlling the brake actuators associated with the rear wheel on one side of the vehicle.